Receiving apparatus equipped with several loudspeakers



Feb. 28, 1939. w. MENNERICH 2,143,994

RECEIVING APPARATUS EQUIPPED WITH SEVERAL LOUDSPEAKERS I Filed Nov. 5, 1936 I WILHELM MENNERICH )fqgmu.

ATTORNEY Patented Feb. 28, 1939 UNITED STATES PATENT OFFICE 2,148,994- REcEIvI NG APPARATUS .EQUIPPED wrrn SEVERAL LOUDSPEAKERS tion of Germany Application November 5, 1936, Serial No. 109,222

' In Germany'November 6,- 1935 4'Clainis. (c1. 179-1) .The invention has as its object an apparatus, in particular a radio apparatus, equipped with a supplementary high-toneloud speaker'an'd a socalled deep-tone loud speaker, The high-tone a loud speaker may in this casebe developed as a.

I cone loud speaker or as a freely radiating membrane loud speaker with" relatively small membrane- The deep-tone loud speaker is either built according to the usual loud speakers or, as special loud speaker for deep tones.

It is the practice of the prior art to provide a tone blender 'wherewith certain frequency ranges:

may be influenced, in particular where the higher frequency ranges are neglected. The action of the soundblender or mixer can the manner. that the high-tone loud speaker can be cut out. This is of particular importance in apparatus where the tone blenderis coordinated to a tube disposed ahead of the end tube. The reason'for this importance lies in the fact that even .with use oi the sound mixer higher ire- .quencies, produced in the end stage by. non-linear distortions due to over-modulation, are favored in as the reproduction through the high-tone loud speaker. The resulting sound image is unfavorably influenced thereby. .The deep-tone loud speaker does practically no longer respond to these interference frequencies and with the cut- .80 ting out of the high-tone loud speaker according 'to the invention a ,conslderable'improvement in tonal quality is accomplished.

The switching out of the high-tone loud speaker is suitably efi'ected jwith the same operating but-- as ton actuating the sound blendera practical. embodiment of such an arrangement is illus-' trated in the drawing. I

The circuit diagram shows basic elements only. The electricseparating filters and sound intensity 4o regulators required for certain cases for the loud speakers are not shown SwitchJ ior'the sound mixer l disposed inthe grid circuit'oi. tube 2 contains a free contact. I leading to high-tone loud speaker I. Parallel .to this latter is connected as deep-tone loud speaker O. 7 As may be, seen from the circuit diagramhigh-tonc loud speaker I is.

connected when the tone mixer is disconnected. As soon the parallel condensers, controlling the high frequencies, oi the tone mixer. are cut in. so the circult'of the high-toneloud speaker is interrupted and solely the so-called deep-toneloud speaker 8 remains in action which is dimensioned in the manner that it, not only transmits the a control circuit included in the in lower but also the high frequencies. Its action corresponds to that of the usual loud speakers for radio apparatus. Higher harmonics occurring by over-modulation of end stage are not favored in the radiation.

. What I claim is:

1. A receiving circuit provided with a last stage amplifier, a pair of loud speakers energized by the amplifier, one 01' said speakers being permanently connected in circuit, the other being 10 adapted to be switched in or out of circuit, a tone control circuit preceding the amplifier, and means for-adjusting the tone control, said adjusting means serving. to alternatively include in circuit either the tone control or the said other loud- 5 be increased in accordance with the, invention in speaker.

'2. A receiving circuit provided with a last stage amplifier, a pair of loud speakers in the output circuitof said amplifier, one radiating the lower audfo frequencies more efiiciently and perma- 20 nently included in circuit and the other radiating the high audio frequencies more efllciently and capable of being switched in or out of circuit, a tone control circuit preceding'the amplifier, and means for adjusting the tone control, said ad- 5 'iusting means serving 'to alternatively includein "circuit either the tone control or the high fre- .'quency loud speaker.

3. A receiving circuit comprising an amplifier, input and output circuits therefor, a sound reproducer included-in the output circuit, a tone t circuit, said tone control including a plurality of condensers 1 and a movable arm capable of connecting in circuit any one of said condensers, a contact in 00- operative relation with said movable arm, and a second sound reproducer connected between said contact and the amplifier-output circuit, whereby either the tone control or the second reproducer may be operated in the alternative. 4. Means for eflecting a faithful reproduction of received signals comprising an audio frequency amplifier, input and output circuits therefor, a loudspeaker responsive to a wide range of audio frequencies included in said output circuit, a seccm! loudspeaker responsive to the higher audio frequencies, and common control means which in one position eilects operation of the second loudspeaker and disconnects the tone control circuit and which in other positions connects the tone mntrol circuit in the amplifier input circuit 1 and disconnects the second loudspeaker. 

